Two authentication methods C# and ASP.NET MVC

I have a login page that I need to have two authentication methods. A normal login, using the ASP.NET MVC controllers and sessions and other that uses the local key cloak with a shared database that I can retrieve the user and the data from there and then authenticate him in the normal database.

So my Startup.cs is this:

public void Configuration(IAppBuilder app)
{
    ConfigureNormalAuth(app);
    ConfigureKeyCloak(app);
}

For the ConfigureKeyCloak method I'm using the UseOpenIdConnectAuthentication.

My question is, how can I edit my Startup.cs to manage if a user clicks on "Entrar" he does the normal ASP.NET MVC login, if he clicks in "Key Cloak" he goes to a different page to login in a shared database.

Thanks in advance

EDIT

This is my code for ConfigureKeyCloak:

public void ConfigureKeyCloak(IAppBuilder app)
        {
            JwtSecurityTokenHandler.DefaultInboundClaimTypeMap = new Dictionary<string, string>();

            app.UseCookieAuthentication(new CookieAuthenticationOptions
            {
                AuthenticationType = "Cookies"
            });

            app.UseOpenIdConnectAuthentication(new OpenIdConnectAuthenticationOptions
            {
                ClientId = clientid,
                Authority = url,
                RedirectUri = redirect,
                PostLogoutRedirectUri = redirect,
                ClientSecret = "20a0b258-b908-4ba4-846b-2b23a6c4a009",
                SignInAsAuthenticationType = "Cookies",
                RequireHttpsMetadata = false,

                Notifications = new OpenIdConnectAuthenticationNotifications
                {
                    AuthorizationCodeReceived = async (context) =>
                    {
                        string authorizationCode = context.Code;
                    }
                }

            });
        }